If you're testing spotting, a couple of extra thing you might be interested in testing is something odd I came across a couple of days ago.
1: Does opening up help spotting if the tanks optics are destroyed?
You'd think that if the tank has lost its optics, it will be almost blind while closed up. But when opening the hatch, the tank commander should still be able to spot quite well using his eyes and binoculars.
However, I had a game where I had a PzIV(70) that had lost its optics, and when I unbuttoned it, it still failed to spot several Shermans driving around and firing about 300m in front of it. This continued for several minutes even though I kept driving the PzIV closer and closer. So it seemed that opening up the hatch didn't help spotting.
2: Does being hull down decrease spotting ability?
In the same game, I had some AFVs in full hull-down position, but they were unable to spot Shermans advancing towards them at long, medium and short range. When I put a Panther in semi-hulldown, it immediately spotted the Shermans. I wanted full hulldown though, so pulled it back a bit. Now it refused to spot anything.
It seemed as if the tanks had their LOS blocked by crops on the field, even though the tank turret was clearly above the level of the crops.